The proposed research is a C13- and F19-nmr study of heme-globin interaction and the conformational processes in the heme pocket which accompany ligand binding to hemoglobin. Hemes will be synthesized which are C13 enriched or F19 labelled specifically at the heme vinyl substituents. These molecules will be used as nmr probes to study the degree to which protein structure affects heme reactivity and the effects of heme ligation state on protein conformation in a mechanistically important region.